Thermostatic switch control mechanism



Aug. 18, 1931. w, B,-BRONANDER 1,819,834

THERMOSTATIC SWITCH CONTROL MECHANISM Filed July 28, 1928 INVENTOR switch to close the alarm circuit.

' shown Patented Aug. 18, 1931 UNITED, STATES PATENT OFFICE 'WILHELM; n. BRONANDER, or monrcmm, NEW JERSEY, ASSIGNOB 'ro scANniA MANUFACTURING COMPANY, OF NEWARK, NEW JERSEY, A CORPORATION 01 NEW JERSEY Application filed zan at,

This invention relates to thermostatic switches particularly adapted for use in fire detectors and alarmsystems.

Thermostatic switches have been used in alarm systems. for causing an alarm to be given in case'o'f fire. Such switches as usually constructed' sometimes cause the alarmv to be given when there is no fire, since a gradual rise in temperature in the atmosphere surrounding the, switch will cause the stance, the switcher detector may be located at the top of a room and on a hot day the air in the room. will become sufiiciently heated to cause the switch to close the alarm circuit. y

This invention has for its salient object to provide athermostatic switch or detector so constructed and arranged that a gradual rise in the temperature of the air surrounding thedectector or switch will not cause the alarm circuit to be closed, but a sudden rise in temperature, such as is experienced in case of fire, would cause the switch to close the circuit, thus giving the alarm.

Another object ofthe invention is to provide a thermostatic switch so constructed and arranged that the device will also act as a thermometer and indicate the temperature.

Further objects of the invention will ap-' pear from the following specification taken in connection with the drawings, which form a part of this application, and in which Fig. 1 is a front elevation of a detector and alarm device constructed ill-accordance with the invention;

Fig. 2 is an end elevation of the device in Fig. 1;

Fig. 3' is a rear elevation, partly in section, of the thermostatic switch;

Fig. 4 is a sectional elevation through the switch taken substantially on line 4-4 of Fig.3;

Fig. 5 is a sectional elevation taken substantially on line 5-5 of Fig. 3; and

Fig. 0 is a diagrammatic view showing the switch and the circuit controlled thereby.

The invention briefly described consists of a thermostatic switch having preferably a For inr THEBMOSTATIC SWITCH CONTROL MECHANISM 1928. Serial No. 296,057.

in a casing and the other element is exposed to the air surrounding the casing. A gradual rise in the temperature of a room where the switch is located will cause a gradual movement of both arms in the same direction and substantially at the same rate of movement. However, a sudden rise in temperature, due to a fire adjacent the switch device, will cause the exposed thermostatic element to move its arm at a' more rapid rate of movement than the rate of movement of the arm connected to the shielded or unexposed element. One of the arms has a portion overlapping the other arm so that an unequal rate of movement of the arms, due to a sudden rise in temperature, will cause one arm to engage the other arm, thus closing the circuit and causing the alarm tobe given.

In order to insure the. sounding of an alarm in case of fire and in case one ofthe thermostatic elements is out of commission, another contact member is disposed in the path of movement of the arms and will complete the circuit under conditions hereinafter explained.

The alarm system may include a bell and a lamp or other devices, if desired.

Further details of the invention will appear from the following description.

In the form of the invention illustrated, the thermostatic switch 10, an alarm bell 11 and a lamp 12, are mounted on a panel 13 carried by a base 14. A casing 15 is secured to the base and to the. panel and houses a battery 16 for supplying the electrical energy of the circuit. l

The thermostatic switch iscarried by a casing comprising a cylindrical body portion or wall 20, preferably formed ofinsulating material, a front cover 21, preferably formed of metal, and a'rear cover 22. If desired, the rear cover may be omitted and the casing can be directly secured to the front of the panel 13, in which case the front surface of the panel will form the rear wall of the casing.

A pair of contact terminals 25 and 26 are secured to the body portion or wall of the casing. The terminal 25 extends through the wall andthe inner end of the terminal has connected thereto a contact strip 28. A coil 30 formed of thermostatic metal is secured at one end, namely, its outer end, to the contact strip 28 and has secured to its inner end a metallic arm 31 which extends substantially radially of the casing.

The cover 21 has formed thereon a laterally extending annular flange 35 having cross strips 36 and 37 secured thereto forming a cage.

A second coil 40, also formed of thermostatic metal, has one end, namely, its outer end 41, secured to the flange 35 and has secured to its inner end and extending outwardly therefrom, an arm 42. The arm 42 extends into the casing and is disposed there in and has its outer end bent laterally as shown at 43. From the showing in Fig. 4, it will be seen that the laterally bent portion 43 of the arm 42 is disposed in overlapping relation with respect to the arm 31. From the showing in Fig. 6 it will be seen that both of the thermostatic coils are wound in the same direction and, therefore, when these coils are subjected to heat, the arms will move in the same direction. It will be noted that the inner end of coil 30 is slightly offset from the inner end of coil and thus, when the arms 31 and 42 engage each other, they have a sliding contact.

A disk 45 of mica or similar material is secured to the rear surface of the front cover 21 of the casing and has an opening 46 through which the portion of the arm 42 connected to the coil 40 extends.

The front cover 21 has formed therein an arcuate slot 50 which ex oses to View portions of the arms 31 an(l '42. One margin of the slot is graduated as shown at 52 and is provided with indicia or marks for indicating temperatures.

The front cover 21 also has secured thereto and extending rearwardly therefrom, a contact pin 55 which is disposed in the path of movement of the arms 31 and 42.

From the showin in Fig. 1 it will be seen that the arm 31, w ich is connected to the thermostatic coil 30 disposedin the casing, is located in advance of the arm 42, these arms being normally spaced apart.

When the temperature in the room in which the switchis located rises gradually, both of the arms 31 and 42 will be moved gradually in an anti-clockwise direction, viewing Fig. 1. Since both arms move together, they will not come into contact with each other and close the alarm circuit.

However, in case of a sudden rise in tem-' perature, due to a fire, the thermostatic coil 40 will be heated much more rapidly than the enclosed or shielded coil 30, thus causing the arm 42 carried by the coil 40 to engage the arm 31 carried by the coil 30. The engagement of the portion -13 of the arm 42 with the arm 31 will Close the alarm circuit and cause an alarm to be given.

If, for any reason, the coil 40 is out of commission, the arm 31 will cause an alarm to be sounded when this arm engages the pin 55. On the other hand, if, for any reason, the coil 30 is out of commission. the arm 42 will engage and move the arm 31 against the pin 55, closing the circuit and causing an alarm to be given.

From the diagram in Fig. 6, it will be seen that the circuit includes both thermostatic coils 30 and 40 and the arms 31 and 42 carried thereby and also includes a source of electrical energy, such as the battery B, the alarm bell 11, and the electric lamp 12. Thus, when the alarm circuit is closed, the lamp will be lighted and the alarm bell will be sounded.

Fromthe foregoing description it will be clear that a simple and practical theremostatic alarm circuit controlling device has been designed and that this device will cause the alarm circuit to be closed in case of fire but will not cause the closing of the circuit in case of a gradual rise in temperature in the room in which the device is located.

Although one specific embodiment of the invention has been particularly shown and described, it will be understood that the invention is capable of modification and that changes in the construction and in the arrangement of the various cooperating parts may be made without departing from the spirit or scope of the invention, as expressed in the following claims.

What I claim is:

1. A thermostatic switch comprising a casing, a pair of relatively fixed contact terminals, an element formed of thermostatic metal connected to each terminal, and an arm secured to each element, said elements being so arranged that said arms will move in the same direction when said elements are subjected to heat, one of said arms having a portion disposed in the path of movement of the other arm, the thermostatic clement having said last named arm connected there to being exposed to the air surrounding the switch and the other element being mounted in said casing and shielded thereby from the surrounding air.

2. A thermostatic switch comprising a casing, a pair of relatively fixed contact terminals, an element formed of thermo-' static metal connected to each terminal,

and anarm secured to each element, said elements being so arranged that said arms will move in the same direction when said elements are subjected to heat, one of said arms having a portion disposed in the path of movement of the other arm, the thermo static element having said last named arm connected thereto being exposed to the air surrounding the switch and the other element being mounted in said casing and shielded thereby from thesurrounding air,

the arm connected to the exposed element being disposed in the rear of the other arm in the direction of movement of the arms underthe action of heat.

3. A detector comprising a casing, a pair of relatively fixed contactterminals mounted therein, a thermostatic element disposed in said casing and having an arm movable in a predetermined direction as said element is heated, a second thermostatic element supported on the outside of said casing, and an arm connected to said second element and extending into said casing, each of said elements being connected to one of said contact terminals, said terminals and first mentioned element being shielded from air and dust by said casing.

4. A detector comprising a casing, a pair of relatively fixed contact terminals mounted thereon, a thermostatic element disposed in said casing and having. an arm movable in a predetermined direction as said element is heated, a second thermostatic element supported on the outside of said casing, and an arm connected to said second element and extending into said casing, each of said elements being connected to one of said contact terminals, said casing. having a slot therein disposed in front of portions of said arms.

5. A detector comprising a casing, a pair of relatively fixed contact terminals mounted thereon, a thermostatic element disposed in said casing and having an arm movable in a predetermined direction as said element is heated, said element being connected to.

one of said terminals, and a contact member disposed in the path of movement of 1 said arm and connected to the other of said contact terminals, andmeans including said casing to shield said element from the atmosphere. o

6. A detector comprising a casing, a pair of relatively fixed contact terminals mounted thereon, a thermostatic element disposed in said casing and having an arm movable in a predetermined direction as said element is heated, said element being connected to one of said terminals, and a contact member mounted externally of the casing and having a portion disposed in the path of movement of said arm and said member being connected to the other of said contact terminals, said casing having a slot therein exposing to view a portion of said arm.

7. A detector comprising a casmg, a; pair of contact terminals mounted thereon, a thermostatic element disposed{ in said casing and having an arm movable in a predetermined direction as said element is heated, said element being connected to one of said terminals, and a contact member mounted second thermostatic element supported on the outside of said casing, and an arm connected to said second element and'extending into said casing, each of said elements being connected to one of said contact terminals, said casing having a slot therein disposed in front of portions of said arms, and having temperature indicating indicia adjacent said slot.

9. A heat controlled switch comprising a pair of heat responsive elements, a pair of relatively fixed contact terminals connected respectively to said elements, said elements being constructed and arranged tomove in the same direction under the action of heat, and a casing for said switch encasing one of said elements and said terminals.

10.- A thermostatic switch comprising a pair of relatively fixed contact terminals; a pair of elements of thermostatic metal, one connected to each terminal, said elements being movable in the same direction under the action of heat, a contact arm connected to each element, and said elements being so arranged that said arms will engage each other with a sliding contact, and a casing for said switch encasing one of said elements and said terminals.

11. A thermostatic switch, comprising a casing having a partition, a pair of heatresponsive elements, one of said elementsbeing disposed inside the partition and the other of said elements being disposed out side of the partition, a pair of relatively fixed contact terminals mounted in said casing inside of the partition and connected respectively to said elements. r

12. A thermostatic switch, comprising a casing having a partition, a pair of heat responsive elements, one of said elements being disposed inside the partition and the other of said elements being disposed outside of the partition, a pair of relatively fixed contact terminals mounted in said casing inside of the partition and connected res ectively to said elements, said elements eing constructed and arranged to move in the same direction under the action of heat.

13. A thermostatic switch, comprising a casing having a partition, a pair of heat responsive elements, oneof said elements being disposed inside the partition and the other of said elements being disposed outside of the partition, a pair of relatively fixed contact terminals mounted on said casing inside of the partition and connected respectively to said elements, said elements being constructed and arranged to move at variable speeds under the action of heat.

14. A thermostatic switch, comprising a casing having a partition, a pair of heat responsive elements, one of said elements being disposed inside the partition and the other of said elements bein disposed outside of the partition, a pair of relatively fixed contact terminals mounted in said casing inside of the partition and connected respectively to said elements, said partition being slotted to permit passage therethrough of a portion of said outside element.

15. A thermostatic switch, comprising a casing having a partition, a pair of heat responsive elements, one of said elements being disposed inside the partition and the other of said elements being disposed outside of the partition, a pair of relatively fixed contact terminals mounted in said casing inside of the partition and connected respectively to said elements, said partition being slotted to permit passage therethrough of a portion of said outside element, and a second slot disposed in front of portions of both arms, said latter slot being covered with a transparent medium.

16. A thermostatic switch, comprising a casing having a partition, a pair of heat responsive elements, one of said elements being disposed inside the artition and the other of said elements being disposed outside of the partition, a pair of contact terminals mounted in said casing inside of the partition and connected respectively to said elements, said partition being slotted to permit passage therethrough of a portion of said outside element, and a second slot disposed in i'ront-of portions of both arms, said latter slot being covered with a transparent medium, said partition having temperature indicating indicia adjacent the last named slot.

17. A thermostatic switch comprising a casing, a pair of contact terminals therein, an outstanding flange on said casing and connected to one of said contact terminals, an element of thermostatic metal within said casing and connected to the other of said terminals, a second element of thermostatic metal within said flange and connected thereto, said elements being movable in the same direction under action of heat, and a contact arm connected to each element, said casing having a partition separatin the thermostatic elements, said thermostatic element within the casing being shielded and said element within the flange being exposed to the surrounding air.

18. A thermostatic switch comprising acasing, a pair of contact terminals therein, a pair of elements of thermostatic metal, one connectedto each terminal, said elements being movable in the same direction under the action of heat, a contact arm connected to each element, one of said thermostatic elements being enclosed by said casing and the other element being mounted externally thereof and exposed to the surrounding air, and a third contact element mounted in said casing in the path of movement of one of said arms.

19. A thermostatic switch comprising a casing, a pair of contact terminals therein, an outstanding flange on said casing and connected to one of said contact terminals, an element of thermostatic metal within said casing and connected to the other of said terminals, a second element of thermostatic metal within said flange and connected thereto said elements being movable in the same direction under action of heat, and a contact arm connected to each element, said casing having a partition separatin the thermostatic elements, said thermostatic element within the casing being shielded and said element within the flange being exposed to the surroundin air, and a third contact element mounted 1n said casing in the path of movement of one of said arms.

In witness whereof, I have hereunto set my hand this 25th day of July, 1928.

' VVILHELM B. BRONANDER. 

